Adding bevel altering the geometry and I can't create loopcuts
That geometry won't be beveled as expected because you're trying to do that on non-planar Ngon consisting of 8 vertices:



Instead dissolve unneeded vertices, and join those on the left to make solid corner:



The selection on the screenshot is an added loopcut which is better to create to avoid Ngon in the middle (however one from the right side is left which is also best to avoid). 

Then there won't be any spikes because the corner will be bevelled equally in all directions.

See also related posts - Bevel tool creating intersecting faces, Can&#39;t bevel an NGon